Objective: To make an epidemiological characterization of nosocomial infections in a high-complexity clinic in the city of Medellin. Methodology: Observational descriptive study with a sample of 1712 patients, who presented nosocomial infection. The quantitative variables were analyzed by means of measures of central tendency, dispersion and position; in turn, the qualitative variables were presented with absolute and relative frequencies. Results: The rate infection was 4.3%; 67.5% occurred in adults. There was a continuous decrease in rate infection from 2010 to 2015 of 35.4%. Surgical site infection was the most common infection with 29%, followed by bacteremia (21%), urinary tract infection (18%) and pneumonia (16%). Adult intensive care unit was the service that showed a greater decrease in the rate of infections reducing from 15% in 2012 to 8% in 2015. Escherichia coli was the most isolated microorganism, followed by Staphylococcus aureus and Klebsiella sp. Conclusions: The data collected evidenced that a proper infection control program is essential in improving the quality of patient care.